package cn.lyjuan.dwz_manage.core.java.util;

import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

import java.util.Map;

/**
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候中取出ApplicaitonContext.
 */
public class SpringContextHolder implements ApplicationContextAware
{
    private static ApplicationContext applicationContext;


    /**
     * 实现ApplicationContextAware接口的context注入函数, 将其存入静态变量.
     */
    public void setApplicationContext(ApplicationContext applicationContext)
    {
        SpringContextHolder.applicationContext = applicationContext;
    }


    /**
     * 取得存储在静态变量中的ApplicationContext.
     */
    public static ApplicationContext getApplicationContext()
    {
        checkApplicationContext();
        return applicationContext;
    }

    /**
     * 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name)
    {
        checkApplicationContext();
        return (T) applicationContext.getBean(name);
    }

    /**
     * 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型.
     * 如果有多个Bean符合Class, 取出第一个.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(Class<T> clazz)
    {
        checkApplicationContext();
        @SuppressWarnings("rawtypes")
        Map beanMaps = applicationContext.getBeansOfType(clazz);
        if (beanMaps != null && !beanMaps.isEmpty())
        {
            return (T) beanMaps.values().iterator().next();
        } else
        {
            return null;
        }
    }

    /**
     * 检查是否注入了 ApplicationContent
     */
    private static void checkApplicationContext()
    {
        if (applicationContext == null)
        {
            throw new IllegalStateException("applicationContext未注入,请在applicationContext.xml中定义SpringContextHolder");
        }
    }

}